1) Field of the Invention
The present invention relates generally to agricultural implements and, more specifically, to structure for lifting and adjusting the down pressure on planter row units.
2) Related Art
Planter row units are typically supported from a transverse frame by vertically spaced parallel arms which permit each row unit to move vertically to follow ground contour. For transport and turning at the end of the field, the entire frame must be lifted, and the lift force and therefore the lift time is substantially more than if individual units alone were raised without moving the frame vertically.
Down force on openers mounted with parallel arms is normally assisted with springs, and adjustments to the down force are made individually by hand for each row unit. Therefore, such adjustments are time-consuming and do not facilitate compensation for changing soil conditions in a given field. Down force can change significantly as the implement encounters irregular terrain.
In some applications, for example when changing from narrowly spaced rows to widely space rows, selected row units may be locked in a lifted position off the ground by utilizing latches. Heretofore, it has been necessary to set a lock up latch and use a pry bar to raise the individual row units to a position wherein the latch will trip automatically to the locking position. A considerable amount of time and effort is expended when a number of the units are locked in the raised position.